This is the story of a man who couldn’t see numbers.
After suffering from a rare degenerative brain disorder, a man was unable to see and identify the numerical digits 2 to 9. If he was presented with a picture of the digit 8 and asked to illustrate what he saw, he drew a scrambled mess of spaghetti-like scribbles with no relation to the number. However, he was able to identify letters and other symbols (even the numbers 1 and 0) as normal.
Reported in the Proceedings of the National Academy of Science, the case study has provided cognitive scientists from Johns Hopkins University with an unprecedented insight into the inner workings of the brain. Most mind-blowing of all, their findings demonstrate how we are capable of processing complex information that we are not necessarily aware of.
The patient, only known as RFS, was previously an engineering geologist and 60 years old at the start of the study. He first started to notice unusual symptoms in late 2010 after suffering from episodes of headaches, loss of vision, and forgetfulness. By August 2011, he was completely unable to recognize, name, copy, or comprehend the digits 2 to 9, regardless of how they were presented (e.g. “6,” “466,” or “A6”).
RFS noted that each time he saw the numbers, a new random arrangement of abstract scribbles would be perceived, meaning he could not learn to identify the digits from the distorted shapes.
“RFS finds the problem quite frustrating... He's a very resilient and smart man, and has been able to take up alternatives and adapt to his 'digit issue' quite well," Teresa Schubert, lead study author from the Cognitive Neuropsychology Laboratory at Harvard University, told IFLScience.
“He had difficulty getting some clinicians to take him seriously at first, so he hopes our study will show people that even very unusual deficits can have a scientific explanation."
Here’s where it gets really strange, however. By studying the RFS’s brain waves with electroencephalography, the researchers revealed that he was processing visual information that he was not aware of. RFS was asked to look at a number with a human face embedded in it. Although he was unable to identify the face embedded in the digits, his brain did detect the presence of a face. In fact, his brain activity was the same as when he was shown a face that he could see clearly.
In a second experiment, RFS was shown images of numbers that had words embedded on them. While he was unaware of the words, brain scans revealed that his nervous system was recognizing the words.
All of this has some deeply intriguing implications. It was previously assumed that visual awareness was closely mirrored by complex neural activity. However, the case of RFS suggests that, in fact, the complex process of detecting and identifying faces, words, or any other visual stimuli is not necessarily linked to one's awareness.
“There are at least two steps that have to occur for you to be aware of seeing something: your brain must detect it, and your brain must do additional processing to bring that thing you detected into your awareness. For RFS, that second process is not working when a digit is present,” explained Schubert.
“The key of this study is understanding what seems like a paradox: How can RFS see digits – and only digits – as spaghetti? Surely, if the brain is recognizing the digits in order to disrupt them, he should be able to recognize them? But we found that the brain detecting a digit, or a face, or a word, is not sufficient for you to actually see that item."